Using an 'old' profile (from 10 minutes ago) instead of 'new'

Just now I 'cleaned' my registry with CC, stupidly enough. Then Firefox opened with asking for the profile. Auch. I tried to merge the backup of the registry, but Windows said there was a problem. Create a new profile??? Rename or delete the profile? I seem to be forced to create a new profile, then go to the profiles directory, and 'use' (or what is this?) the 'old' profile that is there. But that does not help at all. What next? Import settings from the old profile? Do I miss something or is it indeed that difficult? Thanks for pointing out what I have to do. Be sure that this is the last time this will happen to me, syncing, syncing... Hans